Duplicating



y 25, 1967 R. w. GUNDLACH ETAL 3,332,347

DUPLICA'II'ING Filed pril 4. 1962 2 Sheets-Sheet 1 IQH'HF T? Q iumiullll! 1 IE -25 P O W E R S OURCE 24 P OW E R SOURCE INVENTOR ROBERT W. GUNDLACH VSEVOLOD S. MIHAJLOV ciao Q K ATTORNEY Filed April 4, 1962 2 Sheets-Sheet 2 INVENTOR ROBERT W. GUNDLACH BY VSEVOLOD S. MIHAJLOV ATTORNEY United States Patent M 3,332,347 DUPLICATING Robert W. Gunrllach, Victor, and Vsevolod S. Mrha lov,

Rochester, N .Y., assignors to Xerox Corporation, Rochester, N.Y., a corporation of New York Filed Apr. 4, 1962, Ser. No. 185,048 3 Claims. (Cl. 101-469) This invention relates to duplicating processes and, in particular, to the making of duplicates of an original by the action of chemical reagents.

The tremendous amount of paper work involved in business and government administration today has produced a great interest in reducing the annoyance, time and expense of producing multiple duplicates of original copy by present methods. For example, it has been the common practice in clerical work to produce the desired number of copies using carbon paper. This not only increases the difiiculty in handling but also makes it quite difiicult to correct errors since each sheet must be corrected individually. Many duplicating machines are avail able for duplicating printed and other material by processes such as xerography, photo-copying, thermo' and diazo processes. However, each of these processes require apparatus of some substantial complexity and/ or expense. Less expensive duplicating processes such as spirit-duplicating processes and stencil-duplicating processes fall short of the desired characteristics on two points. Operators find that both of these are very messy so that ink or dye stains usually end up on the hands and clothes, and further that the copies made are very poor in image sharpness. This loss of sharpness in the case of spirit duplicating is due to slight bleeding of the dye due to the solvent action on the copy paper. In the case of stencil duplicating, bleeding occurs in the stencil due to the necessary characteristic of the stencil material required to permit passage of ink in the character areas.

Also, it is a common characteristic of the less expensive duplicating processes that they require some form of master or stencil which must be made up as by typing, handwriting, or in a way similar to that for making an original and is itself not suitable for use as an original document. The making of such stencils commonly adds all the disadvantageous effects that are found when using carbon paper in making duplicate copies. Now in accordance with the present invention, it has been found that by using color reagents and evaporation transfer techniques it is possible to greatly simplify low volume duplicating processes. One typewritten copy can be made using a color reagent and the color reagent can then be transferred to a duplicating master quickly, cheaply, and easily without any loss of quality in the typewritten original. Thus, the original continues available for use as an original copy and originals which are received are readily made into multiple copies without impairing the original which in many instances must be preserved. In this manner the use of carbon paper copies is avoided, the use of expensive duplicating equipment is avoided, and high resolution copies can be produced rapidly, cheaply, and neatly. Thus, it is an object of the present invention to define a novel' copying process.

It is a further object of the present invention to define a dry vapor-thermographic duplicating process producing high resolution.

It is a further objective to define means for producing multiple copies of an original by vapor-thermographic techniques.

It is a further object to define a method of producing a duplicating master by direct transfer from an original document without impairing the quality of such original.

Further objects and features of the invention will be- 3,332,347 Patented July 25, 1967 ICC come apparent while reading the following description in connection with the drawings wherein:

FIG. 1 is a cross-sectional view of one embodiment of a typewriter ribbon carrying a color reagent;

FIG. 2 is a face view of a second embodiment of typewriter tape carrying a color reagent;

FIG. 3 is a diagrammatic illustration of simplified apparatus for carrying out one step of the inventive process;

FIG. 4 is a diagrammatic illustration of the simplified apparatus shown in FIG. 3 particularly illustrating a second step in the process;

FIGS. 5 and 6 are diagrammatic illustrations of rotary apparatus for carrying out the process steps shown in FIGS. 3 and 4, respectively;

FIG. 7 is a diagrammatic illustration of a second embodiment of rotary apparatus;

FIG. 8 is a diagrammatic illustration of apparatus using untreated copy paper.

For simplicity of illustration, the invention Will be described using a typewriter to produce the original. As

will be set forth below, however, this is only by way of example and the invention comprehends various other modes of producing the original.

In producing a typewritten original in accordance with the instant invention, the usual typewriter ribbon for a typewriter is replaced with a similar ribbon which has been inked with a conventional typewriter ink and also with a color reagent. This color reagent, which is herein termed Chemical A, may be one of a number of chemicals for which a reaction partner exists so that when the two are combined, an intensely colored substance is formed. The reaction partner is herein termed Chemical B. Following is a partial listing of suitable materials for Chemical A with corresponding reaction partners, Chemical B:

Chemical A Chemical B (1) Pyrocatechol (2) Anflme (1) Iron salts.

(3) Dithiooxamide, N-dimethyl-dithiooxamide, N, N -bis(2-hydroethyl)dithiooxamide, N,N-bis(carb0xymcthybdithiooxamide, other dithiooxamide derivatives.

(4) Hydrozine, pyrogallol, N-(p-Hydroxyphenyl) glycine, Hydroxylamine, Diaminophenol Hydrochloride, p- Methylaminophenol Sulfate, Dichlorohydroquinone, Thiourea, Chlorohydroquinone, Bromohydroquinone, Gallic Acid.

(4) Silver salts.

5 Ammonia salts, Ammonium Benzeate, Ammonium Acetate, Ammonium Carbonate.

(5) Organic diazonium salts and coupler.

As will be further described below, material typed using the ribbon containing Chemical A may be used to form a mirror-image master from which, in turn, multiple direct-reading copies may be produced on paper treated With the corresponding Chemical B.

FIGS. 1 and 2 show various embodiments of typewriter ribbon in accordance with the invention. In FIG. 1, the typewriter ribbon comprises support tape 11 carrying composition 12 of ink and an appropriate Chemical A. Support tape 11 can be any material suitable for use as a typewriter ribbon such as cloth fabric, metal foil, paper, or plastic. Because non-uni-formities are emphasized in a duplicating process, the support tape is preferably of a material that facilitates uniform typing. As is Well known in the typewriter industry, greater uniformity is commonly achieved by using a non-reusable ribbon. Such ribbons are conventionally referred to as carbon ribbons and use a thin plastic support tape. In a preferred embodiment, typewriter ribbon for use in accordance with the present invention comprises a polyethylene film coated with typewriter ink and Chemical A in which Chemical A is about 50% by weight of the ink and Chemical A mixture. Spray coating, roll coating, dip coating, evaporation coating, or other conventional coating means may be used. Alternatively a cloth ribbon is saturated with an ink and Chemical A, of the same nature as for the plastic ribbon, by running the ribbon through a bath of the solution or by some similar process. For example, a silk typewriter ribbon dipped in a mixture of 20 grams rubeanic acid to 100 grams of black typewriter ink.

FIG. 2 shows an embodiment of a typewriter ribbon 14 in accordance with the invention in which one half of the ribbon 15 is coated or permeated with the ink and color reagent solution as in FIG. 1 and the other half of the ribbon 16 is coated with a chalk-like material for correcting errors. The correcting materials are picked for their ability to conceal a typed letter when the same letter is typed over with the error-correcting half of the ribbon, and further for their ability to form a vapor block so that no vapor can issue from the erroneously typed letter. For example, titanium dioxide or zinc oxide in a Wax binder or the like have been found suitable for coating the correction half of the ribbon. Using a ribbon of the type illustrated in FIG. 2 and typing only a single copy increases ease of typing tremendously since the typist does not have to worry about material on carbon copies and, in correcting an error, does not have to use anything outside of the typewriter, itself, such as erasers or other materials available for correcting typewritten material. The typist merely 'backspaces, pushes the ribbon-position lever and retypes the letter in order to obliterate it. Thus, the typists hands are not required to leave the keyboard of the machine in correcting errors.

In accordance with the invention, a single sheet of original typed copy is made using a ribbon in the typewriter corresponding to one of the embodiments illustrated in FIGS. 1 and 2. It is desirable that the typing be highly uniform in order to obtain good copies. Since the average typist does not have good uniformity of touch, an electric typewriter has been found preferable.

FIG. 3 shows a simple manually operated embodiment of apparatus to produce multiple copies of the typed original. This apparatus comprises heat conductive pad 18 such as will maintain a uniform low ambient temperture on its surface when a heated roller is rolled across a sheet of material resting on such surface. Thus the heat conductive pad may be a metal such as aluminum having enough mass to absorb a considerable amount of heat without changing its over-all temperature by a significant amount. This pad should have a surface area adequate to support the largest size of copy sheet that may be desired. A rectangular size of about 10 x 15 inches is adequate for most purposes. The pad should preferably be not less than one quarter inch thick, but this is not limiting since the heat absorption and dissipation characteristics are controlling.

In accordance with the inventive process, master sheet 19 is positioned in contact with the surface of the heat conductive pad. This master sheet may be made of substantially any material that has a smooth finished surface such as a majority of plastic materials, metal foils, glass 3 or paper. By way of example a 1 mil thick sheet of cellulose acetate has been used. Nonporous materials have generally yielded the best results but whether this is due to thermal characteristics, absorption characteristics, or some other characteristics is not fully understood at this time. Thickness of the master sheet is not critical and success has been obtained with sheets of 1 mil and of 15 mils thickness. The determining criteria relevant to this last characteristic are the amount of heat available and the permissible time for vaporizing volatile material from the surface of the master sheet. An excessive thickness will either act as a heat insulator or will dissipate the heat too rapidly for efficient operation. It is preferably less than about 10 mils thick so that it will not absorb or hold an excessive amount of heat. A 5 inch thickness of window glass has been found suitable by way of example.

Typed original 20 is next placed face down against the smooth surface of the master sheet and heated roller 22 or other heat applicator such as a heated plate or heat lamp is used to apply heat against the back of typed original 20. Heat applicator 22, as illustrated, is a metal roller containing thermal element 23 which is connected through handle 24 of the roller to power source 25. In rolling the roller against the back of the typed original or in applying heat in one of the other ways suggested, the intensity of the heat and the length of time must be such as to cause a portion of Chemical A in the characters of the typed original to sublime or otherwise change to a vapor. Suitable heat may be applied by operating the roller at a temperature of about 200 to 400 F. and by rolling the heated roller across the back surface of original 20 at a speed of about /2 to 4 inches per second. With the roller at 240 a speed of about 1 inch per second has been used. These ranges have been found suitable using rubeanic acid as Chemical A. While still higher temperatures produce good results at faster speeds, such temperatures increase the likelihood of heat damage to the materials or equipment. Safeguards against such damage can be built in, but would increase expense. In the apparatus of FIG. 4, heat conductive pad 18- maintains master sheet 19 at a temperature relatively lower than that attained by typed original 20 when the heat is applied to it. Thus, a portion of the color reagent Chemical A is transferred by vaporization and condensation from the typed original to the master sheet. Since the material thus transferred is transferred is between surfaces that are in virtual contact, there is no significant loss of resolution. Since the amount of liquid transferred is ery minute, bleeding effects are practically nonexistent.

After the color reagent, Chemical A, has been thermographically transferred to master sheet 19 as described above in connection with FIG. 3, the master sheet is removed from pad 18. Then as illustrated in FIG. 4, copy sheet 27 treated with Chemical B is positioned on pad 18 with its treated surface facing away from the pad. Copy sheet 27 may comprise any ordinary paper which has been chemically treated in accordance with the invention. Preferably, the paper is smooth surface to permit a more uniform contact in the duplicating process. If the color reagent, Chemical A, is dithiooxamide, otherwise known as rubeanic acid, the copy paper is appropriately treated with a coating solution of, for example, nickel salts dissolved in Water, alcohol or similar solvent to a solution of 5% to 25% by weight volume. For improved density, it has been found advantageous to add an amine in which one or more hydrogen atoms attached to nitrogen have been replaced by one or more alkanol groups. A suitable amount of this additive has been found to be 0.5 to 4.0 moles per mole of nickel. This additive is also advantageously used with the other metallic salts listed under Chemical B. One coating solution used is a 25% solution of NiSO -6H O containing two moles of 2-(2- aminoethyl) aminoethanol per mole of nickel. A solution of 25% weight by volume of copper sulfate in water has also produced effective results. The solution may then be coated on the paper by spraying, dipping, flowing, rolling, wiping or similar process. Some moisture content in the copy paper has been found to increase density further. Thus casein coated papers or paper treated with a humectant such as a sorbitol or glycerine have been found advantageous.

With the treated paper lying face up on the pad, master sheet 19 is positioned in face-to-face Contact with the copy sheet so that the image-carrying surface of the master sheet is in contact with the treated surface of the copy sheet. When now heated roller 22 or similar heat applicator applies heat to the free surface of the master sheet, a portion of the color reagent, Chemical A, in character configuration on the master sheet is transferred by evaporation to the surface of the copy sheet. Where Chemical A contacts the copy sheet, it reacts with its reacion partner, Chemical B, on the copy sheet to produce a visible image.

Since transfers by the process described above are always by face-to-fa-ce contact in the embodiments described above and since the colored product is insoluble, preventing bleeding, a very high resolution is obtainable in the copy.

In a further embodiment of the invention, it is possible to eliminate master sheet 19 described in FIGS. 3 and 4, but with a slight loss in resolution. In this further embodiment, treated copy sheet 27 is placed with its treated surface adjacent to the surface of pad 18. Then typed original 20 carrying Chemical A in its typed characters, is positioned with its typed surface adjacent to the untreated surface of copy sheet 27. When heat is applied as by roller 22 or other heat applicating means, Chemical A vaporizes and condenses on copy sheet 27. If copy sheet 27 is made of a very porous paper or paperlike material, some of the vapor will pass through the pores reaching the treated surface of the copy paper. Otherwise, Chemical A should be chosen as a material that does not sublime but passes through a liquid phase. When this material condenses as a liquid on the untreated surface of the copy sheet, it is absorbed by the copy sheet and passes through in order to react with the reaction partner, Chemical B, on the opposite surface of the copy paper. As is apparent, in order to maintain an acceptable level of resolution, the copy paper in accordance with this embodiment should preferably be quite thin-in the nature of a mil or less. However, thicker copy papers may be used with the attendant disadvantage of slightly lower resolution. A second method for going directly from original to copy requires the use of substantially tranparent copy sheets. The transparent copy sheet carrying Chemical B is positioned with its coated surface facing the type surface of the original. The two are heated causing vaporization and chemical reaction on the contacting surface of the copy sheet. The image is then directly readable through the reverse side of the copy sheet.

FIGS. 5 and 6 show an embodiment of simple rotary apparatus for performing the process illustrated in connection with FIGS. 3 and 4. In this embodiment, cylinder 31 and cylinder 32 perform the functions of pad 18 and roller 22, respectively, of FIG. 3. It is considered preferable that one of the cylinders have a slightly yieldable coating and high friction qualities. For example, covering one cylinder with a surface layer of silicone rubber has been found advantageous. Thus, cylinder 32 is a heated cylinder. In this embodiment, the thermal characteristics of cylinder 31 are not particularly critical. However, it has been found that cylinder 31 because of its close proximity in operation to cylinder 32 is inclined to draw heat from cylinder 32 reducing its temperature and causing non-uniform heat distribution. Thus it is preferable to heat cylinder 31 as well as cylinder 32 as illustrated by thermal elements 23, or to cover cylinder 31 with a heat insulating layer so as to reduce heat dissipation. Good results have also been obtained by heating only cylinder 32, but maintaining the two cylinders in continuous rotating contact for an extended period prior to use so as to reach a point of temperature stability. With the temperature on heated cylinder 32 stabilized in the range between 200 and 400 F., master sheet 19 and typed original 20 are run in between cylinders 31 and 32 and advanced by rotation of the cylinders. Motor 33 is illustrated as driving cylinder 31 through drive means 34. However, it should be understood that the same operation can be performed by a manual crank. As the two sheets run between the two cylinders, heat from heated cylinder 32 penetrates to the characters in the typed original and causes color-reagent Chemical A to vaporize into the minute space between the two sheets. It is pointed out that this minute space is the natural result of positioning two smooth sheets in contact. A mere positioning of two sheets in contact in this manner even when they are run between pressure rollers will not eliminate all space between the contacting surfaces. Minor variations always present in such surfaces prevent complete elimination of such space. As the two sheets pass between the two cylinders, some Chemical A is transferred to the master sheet. The image on the master sheet is commonly a weakly visible image.

While not necessarily limiting as to how the transfer of Chemical A actually takes place, it is theorized that it vaporizes due to the heat between the two sheets and then as the two sheets issue from between the cylinders, they are cooled by the ambient temperature of the air so that condensation or sublimation of Chemical A occurs in part on both surfaces. It has been found that transfers of Chemical A to the master sheet have consistently attained levels of 75% or more transfer. While the reason for this is not completely understood, it is possibly due to the use of master materials which are relatively more heat conductive than the paper used for the original. This would allow the master to cool faster and thus condense the evaporate chemical at a higher rate than the original. It should be noted that in this embodiment there is no requirement as to whether the master sheet or the typed original is in direct contact with the heated cylinder. It is only necessary that enough heat be applied to one or the other so that heat penetrates the sandwich and volatilizes some of the color reagent.

Next, as illustrated in FIG. 6, a treated copy sheet is positioned with its treated surface in contact with the surface of the master sheet now carrying transferred Chemical A in the configuration of the original. The two sheets are advanced as a sandwich between cylinders 31 and 32 in a second vapor-thermographic transfer process similar to that illustrated in FIG. 4. Again the heat may be applied to either surface of the sandwich so long as it is adequate to cause vaporization of some of the Chemical A present on the master sheet. As the two sheets pass between the cylinders, Chemical A is transferred to the copy sheet. While the apparatus of FIGS. 5 and 6 is capable of considerably more automation than that of the highly simplified apparatus illustrated in FIG. 3, is still requires a large extent of manual operation.

FIG. 7 illustrates a relatively automatic machine of inexpensive and simple design. In FIG. 7, cylinder 41 replaces cylinder 31 of FIG. 5 and at the same time, serves as a master sheet. Cylinder 42 is a heated cylinder performing essentially the same operation as cylinder 32 of FIG. 5. Motor 43 is operative to cause rotation of the two cylinders. Positioned in operative relationship to the two cylinders is a supply tray 45, feed means 46, cleaning station 47 and a receiving tray 49. Cylinder 41 comprises a support means 51 and a layer 52 of material suitable as a master sheet. As has been previously described, this material may be a plastic material such as cellulose acetate or a polyester plastic or it may be glass or metal foil but, in the embodiment of FIG. 7, it should have adequate resistance to thermal effects and should have adequate stability and resistance to abrasive wear to permit continuous reuse. Cylinder 42 is heated by thermal element 53 and is constructed with a metallic or similar heat conductive surface layer. Motor 43 in operation rotates cylinder 41 by drive means 55. As illustrated, this drive means also operates feed means 46 and heat cylinder 42. Feed means 46 represents a conventional sheet feeding means as used in common duplicating machines. Treated copy sheets are placed in the supply tray 45 with the treated surfaces up and the type or other original is positioned face up on the top of the pile. Under control of feed means 46, the original is advanced first in between the two rotating cylinders. Heat from cylinder 42 drives the volatile Chemical A from the orginal onto the surface of the master cylinder 41. During this part of the operation, cleaning station 47 is manually positioned out of contact with cylinder 41. As the master sheet on cylinder 41 now carrying the volatile color reagent image rotates around, feed means 46 feeds the first copy sheet in between the two cylinders. This feed means is synchronized with the rotation of the cylinders so that the pattern transferred from the original will come in properly positioned contact with the copy sheet as it is feed in between these cylinders. Heat cylinder 42 will supply sufficient heat through the copy sheet and to the volatile pattern on cylinder 41 to again cause vaporization of a portion of the material so that it comes in contact with the Chemical B on the surface of the copy sheet producing a dense visible image. The copy sheet is then dropped in the receiving tray 49 and cylinder 41 continues around for further duplications. After the desired number of copies has been processed from a given original, cleaning station 47 is brought into operative contact with cylinder 41 so that cylinder 41 is cleaned as it continues to rotate. Cleaning station 47 is illustrated as a tray containing a cleaning solution 56 such as methyl alcohol or acetone. A rotating sponge or web material 57 is positioned so that it revolves through the cleaning solution and also against cylinder 41. For simplicity, the cleaning station has been illustrated as a device for manual positioning in contact or away from cylinder 41. It is to be understood, however, that various means of mechanization as can readily be devised to perform this operation are contemplated. An alternative cleaning means may comprise an infrared lamp or similar source of highly concentrated heat which when directed against cylinder 41 vaporizes the remaining volatile material off its surface. This may also be accomplished by temporarily heating cylinder 41 to a high temperature to completely vaporize any remaining volatile material.

The embodiment of FIG. 7 has a particular advantage in that the original can be placed face up in the feed tray 45 on top of the copy sheets and starting of the machine would then produce the copies in a continuous operation with no further demands on the operator.

A still further embodiment is contemplated in which the copy paper may be ordinary typewriter paper, onionskin or bond and the treatment with Chemical B is performed within the duplicating apparatus. A further variation in this embodiment is the use of a web-type master which may or may not be reusable. Thus, FIG. 8 shows two cylinders of which cylinder 62 is a heated cylinder essentially the same as cylinder 42 in FIG. 7. A second cylinder 61 is driven by a motor 63 which also drives a feed means 66. A feed reel 67 supplies a master web 70 made of polyester plastic, metal foil or other smooth-surfaced flexible web material preferably having thermal and dimensional stability characteristics as described for layer 52 of FIG. 7. For use, the end of the web 70 is drawn over cylinder 61 and fastened in slot 71 in the cylinder with a sufficient amount of web 70 wrapped around cylinder 61 to provide the desired length of master. The master web is chopped off by knife 72 and the master is then ready for use. In operation, the feed tray 65 is filled with a block of paper upon which the original is positioned face down. The original is then fed in under cylinder 62 which heats it so that volatile Chemical A is transferred to the web master 70. Following the original as cylinder 61 comes around for a second revolution, the first copy sheet is fed in off the block of paper in tray 65 and heat from cylinder 62 causes a portion of Chemical A on cylinder 61 to vaporize and transfer to the copy sheet as the copy sheet passes out through exit slot 73. As the copy sheet leaves rollers 61 and 62, it is picked up by rollers 75 and 76 which are driven synchronously with cylinder 61. Roller 76 has a surface layer of felt or other material wettable by a solution of nickel salts or other suitable Chemical B solution. Roller 76 passes through a tray 77 containing the appropirate solution of Chemical B preferably containing an amine as previously discussed. As the copy sheet passes over roller 76, the roller coats the surface of the copy sheet carrying the Chemical A image causing a color reaction in the image portions so that a reproduction of the original appears on the copy sheet. As illustrated, the original sheet as it passes between cylinders 61 and 62 would also be coated with the Chemical B solution. While this would not necessarily have a deleterious effect on the original, it may be desirable and is contemplated that the original be shunted away from between rollers 75 and 76 as by an adjustment of slot 73 to prevent the original from entering the slot. After the original has been run through once, a number of copies can be made from the same master as desired. Then the master can be removed from cylinder 61 and a new master fed from reel 67 onto cylinder 61 for use in duplicating a further original. This use of a new master for each different original eliminates the necessity of a cleaning step such as illustrated in FIG. 7.

In accordance with the present invention, the number of reproduced copies is not strictly limited. However, a preferable quantity is 12 or less since a greater quantity of copies requires a large amount of Chemical A in the original and more accurate control over transfer than would otherwise be necessary. Many known economical machines exist to produce greater volume. It has been found, for example, that to make six copies, it is preferable to have for the average pica character about one microgram of a Chemical A such as rubeanic acid on the intermediate master sheet.

A given original in accordance with the invention is not necessarily limited to producing one master. Although, as has been disclosed, a high percentage transfer of the volatile chemical can be obtained, it is sometimes desirable to produce two masters. Thus, the originator and the recipient of a document might both desire to produce duplications in accordance with the invention. Faster transfers of lower heat will provide only a partial transfer of the volatile chemical for the first master. Enough of the volatile chemical is then retained in the original for making a further master.

While the illustrated embodiments of the invention have been described generally in relation to the reproduction of typewritten material, the invention is in no way limited to typewritten material. Handwritten material using a pen or machine drawn material using some form of stylus device, in which the pen or stylus uses a drawing solution containing color reagent Chemical A, is suit- .able as an original for reproduction in accordance with the inventive process. A usable original may also be produced by xerography from an original that does not contain a volatile color reagent. Such a xerographic copy for use as an original in the inventive process would be made using Chemical A in a deveolper material for the xerographic image. It has been found for example that rubeanic acid, itself, will act as a suitable toner in developing an electrostatic latent image in the xerographic process.

Also is the disclosed embodiments, the source of heat while generally described as a heated roller or cylinder is not limited to such but can be any source of heat capable of supplying the necessary heat to cause vaporization of Chemical A. Thus, photo-lash lamps, infrared lamps, any source of intense radiant illumination, sources for supplying hot air by blowers or convection currents and various electrical heating means are all contemplated as usable with the present inventive process. Various available machines may also be used such as the thermal processing machines available under the trade name, Thermo-Fax, available from Minnesota Mining and Manufacturing Company of St. Paul, Minn.

and the thermal procesing machines available under the trade name Kalfax, available from the Kalvar Corporation of New Orleans, La.

While the present invention has been described as carried out in specific embodiments thereof, there is no desire to be limited thereby, but it is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is:

1. A method of image duplicating comprising the steps of:

(a) forming an original image on a sheet support with an image marking material containing a volatile color reagent which becomes volatile at a first heated temperature significantly above ordinary room tem perature, and a colorant which does not become volatile above said first temperature.

(b) placing said original between a pair of opposed members arranged with facing surfaces a first surface of which is at a heated temperature sufficient to volatize the color reagent from said original to condense onto the second of said surfaces having a non-porous area capable of retaining a received quantity of said condensed color reagent;

(c) after said last recited step placing copy sheets each coated with a color reaction partner of the volatized color reagent of said original sen'atim between the said surfaces to each receive against the coating thereof a portion of the color reagent revolatized from said second surface by the heating effects of said first surface to form on each copy sheet a copy of said original; and

(d) after forming a predetermined number of copies by said last recited step, removing any remaining color reagent from said second surface to renew said second surface for reuse.

2. The method according to claim 1 in which said remaining color reagent is removed from said second surface by the application of a cleaning solution.

3. The method according to claim 1 in which said remaining color reagent is removed from said second surface by the application of heat of intensity sufiicient to volatize the remaining reagent therefrom.

References Cited UNITED STATES PATENTS 2,501,495 3/ 1950 Carroll et al. 101-149.4 2,582,729 1/ 1952 Wassell 101-149.4 2,582,932 1/1952 Lustbader 101-149.4 2,770,534 11/1956 Marx 101-426 2,936,707 5/ 1960 Maguire et al 101-149.4 3,088,028 4/1963 Newman 101-149.5 X 3,094,417 6/1963 Workman.

3,096,867 7/1963 Kuhlman 197-181 3,114,447 12/ 1963 Wolowitz 197-172 3,121,650 2/1964 Meissner 101-426 3,280,735 10/1966 Clark et a1 101-149.4 X

FOREIGN PATENTS 1,279,948 11/ 1961 France.

528,589 11/ 1940 Great Britain.

137,036 3/1961 Russia.

DAVID KLEIN, Primary Examiner. T. D. TAYLOR, Assistant Examiner. 

1. A METHOD OF IMAGE DUPLICATING COMPRISING THE STEPS OF: (A) FORMING AN ORIGINAL IMAGE ON A SHEET SUPPORT WITH AN IMAGE MARKING MATERIAL CONTAINING A VOLATILE COLOR REAGENT WHICH BECOMES VOLATILE AT A FIRST HEATED TEMPERATURE SIGNIFICANTLY ABOVE ORDINARY ROOM TEMPERATURE, AND A COLORANT WHICH DOES NOT BECOME VOLTATILE ABOVE SAID FIRST TEMPERATURE. (B) PLACING SAID ORIGINAL BETWEEN A PAIR OF OPPOSED MEMBERS ARRANGED WITH FACING SURFACES A FIRST SURFACE OF WHICH IS AT A HEATED TEMPERATURE SUFFICIENT TO VOLATIZE THE COLOR REAGENT FROM SAID ORIGINAL TO CONDENSE ONTO THE SECOND OF SAID SURFACES HAVING A NON-POROUS AREA CAPABLE OF RETAINING A RECEIVED QUANTITY OF SAID CONDENSED COLOR REAGENT; (C) AFTER SAID LAST RECITED STEP PLACING COPY SHEETS EACH COATED WITH A COLOR REACTION PARTNER OF THE VOLATIZED COLOR REAGENT OF SAID ORIGINAL SERIATIM BETWEEN THE SAID FURFACES TO EACH RECEIVE AGAINST THE COATING THEREOF A PORTION OF THE COLOR REAGENT REVOLATIZED FROM SAID SECOND SURFACES BY THE HEATING EFFECTS OF SAID FIRST SURFACE TO FORM ON EACH COPY SHEET A COPY OF SAID ORIGINAL; AND (D) AFTER FORMING A PREDETERMINED NUMBER OF COPIES BY SAID LAST RECITED STEP, REMOVING ANY REMAINING COLOR REAGENT FROM SAID SECOND SURFACE TO RENEW SAID SECOND SURFACE FOR REUSE. 